Introduce a BuiltinsConstructStub that sets up new.target and does a [[call]] per ES6 9.3.2

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index cacde85f1fbf4a31e2191ce7d1f6655ad0ac4ee7..65a0add68411dcbc2148381ebba44432c7e350fd 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -434,6 +434,7 @@ const int kStubMinorKeyBits = kSmiValueSize - kStubMajorKeyBits - 1;
   V(JS_ITERATOR_RESULT_TYPE)                                    \
   V(JS_WEAK_MAP_TYPE)                                           \
   V(JS_WEAK_SET_TYPE)                                           \
+  V(JS_PROMISE_TYPE)                                            \
   V(JS_REGEXP_TYPE)                                             \
                                                                 \
   V(JS_FUNCTION_TYPE)                                           \
@@ -732,6 +733,7 @@ enum InstanceType {
   JS_ITERATOR_RESULT_TYPE,
   JS_WEAK_MAP_TYPE,
   JS_WEAK_SET_TYPE,
+  JS_PROMISE_TYPE,
   JS_REGEXP_TYPE,
   JS_FUNCTION_TYPE,  // LAST_JS_OBJECT_TYPE, LAST_JS_RECEIVER_TYPE
 
@@ -7706,6 +7708,12 @@ class JSRegExp: public JSObject {
   DECL_ACCESSORS(flags, Object)
   DECL_ACCESSORS(source, Object)
 
+  static MaybeHandle<JSRegExp> New(Handle<String> source, Handle<String> flags);
+
+  static MaybeHandle<JSRegExp> Initialize(Handle<JSRegExp> regexp,
+                                          Handle<String> source,
+                                          Handle<String> flags_string);
+
   inline Type TypeTag();
   inline int CaptureCount();
   inline Flags GetFlags();